Design and construction of a hydronic conditioning loop for a psychrometric testing facility

Abstract

Heat exchanger effectiveness is a major contributor to overall system performance, yet heat exchangers are often the least understood component of the cycle. The major contributing factor to the current gap in heat exchanger knowledge is directly attributed to the difficulty of full scale heat exchanger testing. A novel facility is being constructed at Oklahoma State University to allow the investigation of large commercial heat exchanger coils. Data collected will include baseline performance with different refrigerants, heat exchanger modifications, and frosting scenarios. To collect this data steady-state testing conditions are achieved through the use of a closed loop facility with an integrated air conditioning system.

The role of the conditioning system is ensuring the air passing over the heat exchanger being tested is held at constant temperature and humidity per the heat exchanger testing requirements. This is achieved through the use of heat pumps connected to heat exchangers supplemented by additional downstream conditioning equipment. Currently the conditioning equipment will allow testing from 0°F to 140°F with approximately 30 tons of capacity at 70°F inside air temperature. Utilizing the new facility, coil manufacturers will be able to quickly evaluate new design implementations and refrigerants which will further the advancement of technology in this important field.